Preliminary tests revealed a drug in Woolmer's system that would have incapacitated him, reported Panorama. The show said it seems certain that as 6ft 2ins Woolmer was being strangled, he had already been rendered helpless.

The final results of the toxicology tests are due to be handed back to Jamaican police next week, but are expected to confirm the preliminary findings, the investigative programme said.

The 58-year-old coach was found unconscious in the Pakistan team's hotel in March, a day after his side lost to Ireland in a humiliating defeat which knocked them out of the World Cup.

Details of the poison could hold a significant clue to finding his killer.

The BBC1 show said chief investigating officer Mark Shields felt it would be difficult to strangle a man of Woolmer's size. He told the BBC: "Bob Woolmer was a large man and that's why one could argue that it was an extremely strong person, or maybe more than one person. But equally the lack of external injuries suggests that there might be some other factors and that's what we're looking into at the moment."

Mr Shields said last week that the "huge and complex" inquiry needed more time before naming any suspects. A suspected heart attack was the first suggested cause of Woolmer's death but initial post-mortem results were inconclusive and the rumour mill went into overdrive.

Theories surrounding the mystery of the "gentle giant's" death ranged from potential links to match fixing allegations to a fan with a grudge. Panorama examined whether religious beliefs could have a bearing on the case.

The team's former media manager, PJ Mir, said that Woolmer agreed with Mir's view. This was that senior members of the squad, some members of the strict Muslim movement Tablighi Jamaat, were more focused on religion than cricket.

Mir told the programme: "He wasn't particularly pleased when players were going out to say their prayers in the middle of the game...and a substitute was coming in."

Mir told the programme that a fatwah has been issued against him, forcing him to flee the country - and believes Woolmer might have faced a similar level of anger.